Way to much fabrication, in my opinion. Especially if you haven't done anything like this before. I think it would cost a lot more too. If you want a front wheel drive pickup, just buy a 4wd and remove the rear drive shaft.
Seriously, I'd sell the Caddy for whatever you can get. It may not be much, but maybe enough to buy a wrecked car or pickup with a drivetrain that would bolt into the pickup.